I am very happy to share that my work on active deformations of lipid vesicles is finally out in Nature Physics. A nicer thread+movies coming soon, in the meantime:
www.nature.com/articles/s41...

Thx to Andreas, Hammad, Dmitry, Gerhard @laynefrechette.bsky.social and everybody else who contributed!

If the DSS is through filament transport in 3D then severing those bundles in the middle of the well should stop it. So we performed laser ablation and *zap* the bundles are gone and the DSS contracts and dies out.

Well apparently yes! The network uses its 3D architecture to "suck" filaments at the center and "inject" them back at the periphery - again, we show this with tracking filaments in 3D. But it's barely visible in the data, so we developed a killer experiment ;-) go to the next block to see it..

Well, if it is not nucleation and it is not transport in 2D, we might as well take a look at the network architecture in 3D! Using confocal we observe this weird tent-like structure - is it possible that filaments are transported through it?

It's not actin turnover, the classical answer: this DSS works in the absence of actin nucleators or in the presence of phalloidin, i.e. with stabilized filaments. No depolymerization is present. So it has to be transport of the filaments. We combine a bunch of techniques to observe it, like speckle.

... and we got this: continuous actin contraction for hours and hours without collapse to the center. We also show how the flow and the actin architecture are organized in space in a regular way.
The question is... what is sustaining this dynamic state? What "compensates" for this contractile flow?

Problem is, traditionally reconstituted actomyosin networks just to a big whooooosh and quickly contract to a single point.

This is the actin cytoskeleton in a cell (by A. Schaeffer). Actin structures arecontinuously renewed, contracted and dissassembled in cells, to create architectures that have always the same "shape" but are microscopically fueled by fluxes of new material. We call it a dynamic steady state (DSS).

New preprint out 🔥🔥 on my postdoc work with @manuelthery.bsky.social and @lblanchoin.bsky.social about how we can create sustained dynamic steady states of actin network inside microscopic wells that contract "forever" without collapsing! A thread 🧵
www.biorxiv.org/content/10.1...

It's the time of the year when I make a Christmas themed experiment to celebrate another year gone by: this year, a micropatterned branched actin network with myosin, aka a Christmarp(2/3) tree, doing weird stuff. Happy holidays Bluesky! 🥳🥳🥳